You're not alone: no-one knows and no-one really understands. Certainly, as an actor and playwright, Shakespeare needed to be at the hub of social and Court life, which was London; there is speculation that Shakespeare was almost forced into a loveless marriage to Anne Hathaway because he had got her pregnant and he used his career as an excuse to avoid her; there is speculation that Shakespeare continued to court various female companions in London whilst married. The fact that Shakespeare only left his wife their second best bed in his will is often interpreted as some form of rebuke to her.

Carol Ann Duffy and Germaine Greer, however, both imagine the married life of Shakespeare to have been loving and caring, despite perhaps occasional lapses in behaviour. Duffy's poem "Anne Hathaway" is an intersting read which interprets the second-best bed as being the marital bed and a sign of intimacy. Greer relies on historical traditions and parallels to show that it was unlikely that Hathaway would have been abandoned by Shakespeare. Instead, she presents Hathaway as an extremely capable, business-minded and practical woman.

References:

Carol Ann Duffy "Anne Hathaway" The World's Wife

Germaine Greer "Shakespeare's Wife"

You are not the first to have so many questions about Shakespeare's private life.  The truth is, we have very little reliable information about his life before he moved to London.  The most probable reason that caused him to leave his home, his wife, and his children is the death of little Hamnet.  We don't know for sure, but I also believe that Shakespeare loved his family, and a death of a young child is always traumatic even though it was far more common in Shakespeare's time than in ours.  It is also possible that he left for the city in order to better provide for his family.  There was more opportunity for making money in the city than in the countryside, and as history has shown us, Shakespeare's work became very lucrative as he became more well-known.